Steam generators are generally composed of an elongate vessel containing a bank of tubes. A heat transfer fluid circulates in the vessel and gives up its heat to water circulating in the bank of tubes in order to convert it into steam. The tubes of the bank of tubes generally pass out of the steam generator at both ends; pressurized water is introduced at one of their ends and the superheated steam passes out at the other end. Headers collect the steam coming from the tubes of the bank.
The invention relates more particularly to the connection of the steam outlets of the tubes of the tube bank to the steam headers.
Various arrangements have already been proposed for the connection of these tubes to the steam headers, but these arrangements do not generally permit easy intervention when these tubes have to be subjected to leaktightness tests.
Thus, connections of a general T-shape, connecting the steam outlet tubes of a generator to the headers, are already known, for example from French Pat. No. 1,592,203 they are composed on the one hand of a straight length of tube, one end of which is connected to the end of the steam outlet tube, while its other end is closed with the aid of a removable stopper, and on the other hand of a side branch extending from the central portion of the straight length and connected to the steam headers. When it is desired to introduce a tracer gas into a tube of the bank of tubes, for example in order to check its leaktightness, the stopper closing the end of the straight portion of the corresponding connection is removed and in its place is connected a pipe introducing the tracer gas into the connection and consequently into the corresponding tube. With an arrangement of this kind, all the connections must necessarily be provided with a removable stopper of this kind, so that there is a very large number of stoppers, one for each connection, since it is not possible to tell in advance which tube will require intervention. However, intervention on a connection for the purpose of introducing a tracer gas is an exceptional operation, which is carried out very rarely and on a very limited number of connections, so that the steam generator is thus provided with a large number of removable stoppers the majority of which will probably remain in position throughout the entire life of the installation. This large number of removable stoppers raises the cost price of the installation and reduces its reliability in respect of leaktightness, without really improving the ease of intervention for the purpose of leak detection.
The present invention makes it possible to obviate these various disadvantages.